The invention relates to a device for applying a filament winding to a support of any shape, employing at least two robot arms controlled by a preprogrammed device, as well as a universal winding machine comprising an application thereof.
One filament winding technique consists in causing a head for dispensing synthetic or other fibres or threads, preimpregnated or otherwise, to describe a programmed trajectory in the vicinity of a support in such a way that the said fibres or threads are placed under tension at the desired point thereon, by unwinding from storage reels. Filament winding is followed by impregnation with resin when the fibres are not preimpregnated, and the final composite material is obtained after polymerization of the fibre-resin combination. This filament winding is performed, for example, on a solid or hollow mandrel the outer shape of which corresponds to the inner shape of the hollow articles to be produced. When this mandrel is full, it must be possible to withdraw it when the article is formed, which is why it is often made of an agglomerate material, hardenable under ambient atmospheric conditions, but destructible after thermal cycles, for example chemically. When the mandrel is hollow, it is usually formed of a rigid envelope of metal or the like which remains inside the article after polymerization. For winding, the said mandrel is placed on a machine and is generally caused to perform a rotational movement drawing off, by winding it onto itself, the fibre from a reel, itself caused to perform the complementary movements necessary for covering the said mandrel. The articles obtained using machines of this kind are envelopes of a shape that is spherical or cylindrical with dished ends having one or two orifices necessary for their utilization and through which passes the mandrel supporting shaft during filament winding.
For the production of tubes of composite materials, there are also known machines that use a frame rotating about a tube caused to perform a feed movement in relation to the said frame. These machines can thus provide windings about articles tending to be of a spherical or tubular shape, but cannot easily wind around articles of a toroidal shape. For winding filaments around a toroidal element, there is known a device the principle of which consists in causing the said toroidal element to be supported by a train of rolls on which it rotates about its axis, and in causing a material guiding device to rotate about the surface of the toroidal element, a relative movement being generated between the guiding device and the toroidal element so that the material is wound around, a device being provided to compensate for the change in direction of the toroidal element as a result of the winding of the elongated material over the latter, as described in FR A 2 225 372.
In this kind of machine for winding around toric mandrels, there is necessarily a frame for carrying the reels of fibres that passes through the inside of the torus after the fashion of two successive links in a chain. In order to perform the winding, this frame necessarily has to be opened to cause it to enter the torus and then adjusted therein before recommencing the reverse action at the end of winding. This entails difficult assembly and heavy, voluminuous auxiliary means. In addition, if there is an obstacle on the toric support, for example a diametrically arranged crossmember, winding has to be interrupted and the frame has to be displaced before winding can be resumed on the other side of the obstacle. As a result, if one wishes for an article of this type of if, generally speaking, one wishes to obtain by filament winding an article comprising one or more obstacles to continuous winding, the use of a dispensing head or of a dispensing frame proves practically impossible. There is also known from FR-A 2 537 556 a device suitable for providing windings on toric supports the principle of which consists in displacing a dispensing reel in axial translation inside the toric support with the help of a mobile arm, in receiving and displacing the said reel upwards, with the help of a second mobile mechanism, so that it can be taken up by a third mechanism using an arm identical to the first one and displaceable in translation parallel to the outside of the toric support, the reel being finally taken up by a fourth member which replaces it on the original arm.
It is easy to imagine that, to ensure correct winding under constant tension from these four reel carrying mechanisms, each of which has to move along a precise trajectory, the problems of synchronization are not easy to solve, not to mention the complexity of the arrangements of these mechanisms.
Furthermore, with the machines described above, it is difficult to change over from one article to an other, if these articles are not of the same shape and size, without modifying or replacing the frame and even the mandrel support. Finally, the toroidal elements in question must have at least a regular external shape in order to be able to rotate easily on their support rolls during the winding operation. These machines are thus suitable for producing series of identical toroidal articles but they are obviously too complex to be used to form, for example, assemblies of tubular parts. Conversely, the machines for forming articles tending to be of a spherical or tubular shape, mentioned earlier, are quite incapable of processing irregular toroidal articles or other articles of any shape at all.